Vacuolar Interface Dermatitis

Key Features:

■ Relatively sparse inflammatory cell infiltrate that obscures the dermoepidermal junction

■ Vacuolar alteration of basal keratinocytes + necrotic keratinocytes

■ Infiltrate may be only in the superficial dermis, or in both the superficial and deep dermis

Clinical Presentation: Erythema Multiforme Minor:

Synonym: von Hebra's disease.

■ Acute, self-limited, recurrent disease of the skin and mucous membranes, most commonly in response to infection with herpes simplex virus types I and II

■ Pleomorphic eruption with erythematous and violaceous macules, papules, urticarial plaques, vesicles and bullae, and targetoid or iris lesions, in which an erythematous patch or urticarial plaque surrounds a central bulla or dusky macule

■ Lesions distributed symmetrically with a predilection for the distal extremities

Erythema Multiforme Major:

Synonyms: Stevens-Johnson syndrome; toxic epidermal necrolysis (TEN) spectrum; Lyell's syndrome (eponym for TEN).

■ Acute, severe, sometimes fatal systemic disease, with involvement of skin and several mucous membranes, associated with fever; most commonly drug-induced

■ Generalized, tender erythema, which quickly progresses to bulla formation with extensive separation of the epidermis in sheets

■ Erosive mucosal lesions

Histology:

■ Similar for erythema multiforme minor and major

■ Vacuolar alteration of the basal keratinocytes, which may progress to frank subepidermal vesiculation (Figs. 1A-C)

■ Necrotic keratinocytes that may be individual or confluent; in TEN, there is confluent, full-thickness epidermal necrosis (Fig. 1D)

■ Sparse perivascular lymphohistiocytic infiltrate in superficial to mid dermis obscures dermoepidermal junction

■ Basket-weave stratum corneum (Figs. 1C and D)

Immunofluorescence: Direct Immunofluorescence:

■ Homogeneous staining for IgM (and sometimes granular staining for C3) of intraepidermal cytoid bodies (fluorescent keratinocytes)

■ Granular staining for C3 and fibrinogen along the dermoepidermal junction

Clinicopathologic Correlation:

Clinical Feature

Histopathologic Correlate

Dusky center of

Necrotic keratinocytes

target lesion

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